18 results on '"Balthazar CH"'
Search Results
2. Sentences Are Key: Helping School-Age Children and Adolescents Build Sentence Skills Needed for Real Language.
- Author
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Balthazar CH and Scott CM
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- Child, Humans, Adolescent, Language Tests, Language, Linguistics, Comprehension, Language Development Disorders diagnosis, Language Development Disorders therapy
- Abstract
Purpose: In this article, we present key concepts pointing to the importance of targeting complex sentences for school-age children and adolescents with developmental language disorders (DLD). Drawing on current treatment research, we argue that the sentence is a crucial but often neglected piece of the puzzle when it comes to understanding relationships between DLD and academic outcomes. We provide detailed suggestions for how clinicians can focus on complex sentence structures in natural academic contexts to bridge this gap., Method: Background information on sentence complexity is presented, along with a rationale for targeting complex sentences with school-age children and adolescents with DLD. Intervention methods from a variety of studies targeting multiclausal sentences are discussed in relation to current accounts of language learning and language processing models. We provide a robust catalog of suggested strategies for targeting sentence complexity in a manner that is aligned with research findings to date and integrated into real academic contexts., Conclusions: Complex sentence structures are a key challenge for students with DLD as they tackle discipline-specific language and academic tasks. Sentence complexity treatment programs employ one or more treatment methods including priming, modeling, recasting, contextualization, metalinguistic instruction, and sentence combining. While studies have consistently shown a measurable improvement in complex sentence production on proximal outcomes regardless of treatment approach, evidence of durable, functional changes for students with DLD remains sparse. We encourage new treatments that target comprehension and production of complex sentences in real-life academic contexts in clinical practice and research., Supplemental Material: https://doi.org/10.23641/asha.23969103.
- Published
- 2024
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3. Explicit Grammatical Intervention for Developmental Language Disorder: Three Approaches.
- Author
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Balthazar CH, Ebbels S, and Zwitserlood R
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- Adolescent, Child, Child Language, Child, Preschool, Humans, Language Development Disorders therapy, Language Therapy methods, Linguistics
- Abstract
Purpose This article summarizes the shared principles and evidence underpinning methods employed in the three sentence-level (syntactic) grammatical intervention approaches developed by the authors. We discuss associated clinical resources and map a way forward for clinically useful research in this area. Method We provide an overview of the principles and perspectives that are common across our three syntactic intervention approaches: MetaTaal (Zwitserlood, 2015; Zwitserlood, Wijnen, et al., 2015), the SHAPE CODING system (Ebbels, 2007; Ebbels et al., 2014, 2007), and Complex Sentence Intervention (Balthazar & Scott, 2017, 2018). A description of each approach provides examples and summarizes current evidence supporting effectiveness for children with developmental language disorder ranging in age from 5 to 16 years. We suggest promising directions for future research that will advance our understanding of effective practices and support more widespread adoption of syntactic interventions with school-age children. Conclusion In each approach to syntactic intervention, careful and detailed analysis of grammatical knowledge is used to support target selection. Intervention targets are explicitly described and presented systematically using multimodal representations within engaging and functional activities. Treatment stimuli are varied within a target pattern in order to maximize learning. Similar intervention intervals and intensities have been studied and proven clinically feasible and have produced measurable effects. We identify a need for more research evidence to maximize the effectiveness of our grammatical interventions, encompassing languages other than English, as well as practical clinical tools to guide target selection, measurement of outcomes, and decisions about how to tailor interventions to individual needs.
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- 2020
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4. Whole Body Vibration Training on Muscle Strength and Brain-Derived Neurotrophic Factor Levels in Elderly Woman With Knee Osteoarthritis: A Randomized Clinical Trial Study.
- Author
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Simão AP, Mendonça VA, Avelar NCP, da Fonseca SF, Santos JM, de Oliveira ACC, Tossige-Gomes R, Ribeiro VGC, Neves CDC, Balthazar CH, Leite HR, Figueiredo PHS, Bernardo-Filho M, and Lacerda ACR
- Abstract
Background : Osteoarthritis of the knee (kOA) is a chronic, progressive, degenerative health condition that contributes to the imbalance between the synthesis and destruction of articular cartilage. Recently, whole body vibration (WBV) training has been recommended as an effective alternative for strength training in elderly people, and various physiological effects are obtained in response to exercise performed on a vibratory platform, such as an increase in muscle activation and improved muscle performance. However, the effects of WBV particularly on the strength of the quadriceps muscle and neuronal plasticity are unknown. Objective : The aim of this study was to evaluate the effects of adding WBV to squat training on the isometric quadriceps muscle strength (IQMS) and the plasma levels of brain-derived neurotrophic factor (BDNF) in elderly woman with kOA. Methods : Fifteen elderly women ≥65 years of age with kOA were randomized into two interventions: (1) the vibration group (VG), in which participants performed squat exercise training in association with WBV or (2) the exercise group (EG), in which participants performed squat exercise training without vibration, for 12 weeks 3×/week. Results : Compared to the EG group, the VG group demonstrated a significantly greater delta (Δ) in IQMS values (IC95% 0.43-7.06; p ≤ 0.05) and in Δ BDNF plasma levels (IC95% -32.51 to 4.217; p ≤ 0.05) after the intervention period. There was an association between increase of Δ BDNF plasma levels and increase of Δ IQMS ( β = 0.57; R
2 = 0.32; p = 0.03). Conclusion : The addition of WBV to squat exercise training improves lower limb muscle performance in elderly women with kOA. These findings suggest that the improvement in muscle performance is related to neuromuscular adaptations induced by WBV. Clinical Trial Registration : www.ClinicalTrials.gov, identifier NCT03918291.- Published
- 2019
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5. Effects of the inspiratory muscle training and aerobic training on respiratory and functional parameters, inflammatory biomarkers, redox status and quality of life in hemodialysis patients: A randomized clinical trial.
- Author
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Figueiredo PHS, Lima MMO, Costa HS, Martins JB, Flecha OD, Gonçalves PF, Alves FL, Rodrigues VGB, Maciel EHB, Mendonça VA, Lacerda ACR, Vieira ÉLM, Teixeira AL, de Paula F, and Balthazar CH
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- Adult, Biomarkers analysis, Fatigue blood, Fatigue etiology, Fatigue physiopathology, Female, Humans, Inflammation blood, Inflammation etiology, Kidney Failure, Chronic complications, Male, Maximal Respiratory Pressures, Middle Aged, Muscle Strength, Quality of Life, Surveys and Questionnaires, Treatment Outcome, Breathing Exercises methods, Fatigue rehabilitation, Kidney Failure, Chronic therapy, Renal Dialysis adverse effects, Respiratory Muscles physiopathology
- Abstract
Objective: Evaluate and compare the isolated and combined effects of Inspiratory Muscle Training (IMT) and Aerobic Training (AT) on respiratory and functional parameters, inflamatory biomarkers, redox status and health-related quality of life (HRQoL) in hemodialysis patients., Methods: A randomised controlled trial with factorial allocation and intention-to-treat analysis was performed in hemodialysis patients. Volunteers were randomly assigned to performe 8-weeks of IMT at 50% of maximal inspiratory pressure (MIP), low intensity AT or combined training (CT). Before the interventions, all the volunteers went 8-weeks through a control period (without training). Measures are taken at baseline, 8-week (after control period) and 16-week (after the interventions). Primary outcomes were functional capacity (incremental shuttle walk test), MIP and lower limbs strength (Sit-to-Stand test of 30 seconds). Plasma levels of interleukin-6 (IL-6), soluble tumor necrosis factor receptor 1 (sTNFR1) and 2 (sTNFR2), adiponectin, resistin and leptin, redox status parameters and HRQoL (KDQOL-SF questionnaire) were the scondary outcomes. Data analyses were performed by two-way repeated measurements ANOVA., Results: 37 hemodialysis patients aged 48.2 years old (IC95% 43.2-54.7) were randomized. Increase of MIP, functional capacity, lower limbs strength and resistin levels, and reduction of sTNFR2 levels in 16-week, compared to baseline and 8-week, were observed in all the groups (p<0.001). IMT improved functional capacity, MIP and lower limbs strength in 96.7m (IC95% 5.6-189.9), 34.5cmH2O (IC95% 22.4-46.7) and 2.2repetitions (IC95% 1.1-3.2) respectively. Increase in resistin leves and reduction in sTNFR2 leves after IMT was 0.8ng/dL (IC95% 0.5-1.1) and 0.8ng/dL (IC95% 0.3-1.3), respectively, without between-group differences. Compared to baseline and 8-week, adiponectin levels (p<0.001) and fatigue domain of the HRQoL (p<0.05) increased in 16-week only in CT., Conclusion: IMT, AT and CT improved functional parameters and modulated inflammatory biomarkers, in addition, IMT provoked a similar response to low intensity AT in hemodialysis patients., Trial Registration: Registro Brasileiro de Ensaios clínicos RBR-4hv9rs., Competing Interests: The authors have declared that no competing interests exist.
- Published
- 2018
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6. Targeting Complex Sentences in Older School Children With Specific Language Impairment: Results From an Early-Phase Treatment Study.
- Author
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Balthazar CH and Scott CM
- Subjects
- Adolescent, Child, Comprehension, Female, Humans, Language Tests, Linguistics, Male, Reading, Reproducibility of Results, Treatment Outcome, Writing, Language Development Disorders therapy, Language Therapy methods
- Abstract
Purpose: This study investigated the effects of a complex sentence treatment at 2 dosage levels on language performance of 30 school-age children ages 10-14 years with specific language impairment., Method: Three types of complex sentences (adverbial, object complement, relative) were taught in sequence in once or twice weekly dosage conditions. Outcome measures included sentence probes administered at baseline, treatment, and posttreatment phases and comparisons of pre-post performance on oral and written language tests and tasks. Relationships between pretest variables and treatment outcomes were also explored., Results: Treatment was effective at improving performance on the sentence probes for the majority of participants; however, results differed by sentence type, with the largest effect sizes for adverbial and relative clauses. Significant and clinically meaningful pre-post treatment gains were found on a comprehensive oral language test, but not on reading and writing measures. There was no treatment advantage for the higher dosage group. Several significant correlations indicated a relationship between lower pretest scores and higher outcome measures., Conclusions: Results suggest that a focused intervention can produce improvements in complex sentence productions of older school children with language impairment. Future research should explore ways to maximize gains and extend impact to natural language contexts., Supplemental Material: https://doi.org/10.23641/asha.5923318.
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- 2018
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7. Different levels of brain-derived neurotrophic factor and cortisol in healthy heavy smokers.
- Author
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Neves CDC, Lacerda ACR, Lima LP, Lage VKS, Balthazar CH, Leite HR, and Mendonça VA
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- Adult, Analysis of Variance, Case-Control Studies, Enzyme-Linked Immunosorbent Assay, Humans, Immunoenzyme Techniques, Male, Nicotine adverse effects, Nicotine metabolism, Reference Values, Saliva chemistry, Smoking adverse effects, Statistics, Nonparametric, Time Factors, Tobacco Products adverse effects, Brain-Derived Neurotrophic Factor blood, Hydrocortisone analysis, Smoking metabolism
- Abstract
Studies suggest that brain-derived neurotrophic factor (BDNF) and the hypothalamic-pituitary-adrenal (HPA) axis modulate dopaminergic activity in response to nicotine and that the concentrations of BDNF and cortisol seem to be dependent on the amount and duration of smoking. Therefore, we investigated BDNF and cortisol levels in smokers ranked by daily cigarette consumption. Twenty-seven adult males (13 non-smokers and 14 smokers) participated in the study. The smokers were divided in two groups: light (n=7) and heavy smokers (n=7). Anthropometric parameters and age were paired between the groups, and plasma BDNF and salivary cortisol levels were measured. Saliva samples were collected on awakening, 30 min after awakening, at 10:00 and 12:00 am, 5:00 and 10:00 pm. Additionally, cotinine serum levels were measured in smokers. Heavy smokers had higher mean values of BDNF compared to the control group (P=0.01), whereas no difference was observed in light smokers. Moreover, heavy smokers presented lower cortisol levels in the last collection (10:00 pm) than the control group (P=0.02) and presented statically higher values of cotinine than the light smokers (P=0.002). In conclusion, changes in BDNF and cortisol levels (10:00 pm) appear to be dependent on heavy cigarette smoking and can be involved in activation and in the relationship between the mesolimbic system and the HPA axis.
- Published
- 2017
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8. The role of the inspiratory muscle weakness in functional capacity in hemodialysis patients.
- Author
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Figueiredo PH, Lima MM, Costa HS, Gomes RT, Neves CD, Oliveira ES, Alves FL, Rodrigues VG, Maciel EH, and Balthazar CH
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- Cross-Sectional Studies, Female, Humans, Inspiratory Capacity, Kidney Failure, Chronic complications, Male, Middle Aged, Muscle Strength, Muscle Weakness etiology, Oxygen Consumption, Exercise Tolerance, Kidney Failure, Chronic physiopathology, Muscle Weakness physiopathology, Renal Dialysis adverse effects, Respiratory Muscles physiopathology
- Abstract
Introduction: Inspiratory muscle function may be affected in patients with End-Stage Renal Disease (ESRD), further worsening the functional loss in these individuals. However, the impact of inspiratory muscle weakness (IMW) on the functional capacity (FC) of hemodialysis patients remains unknown. Thus, the present study aimed to evaluate the impact of IMW on FC in ESRD patients undergoing hemodialysis., Materials and Methods: ESRD patients on hemodialysis treatment for more than six months were evaluated for inspiratory muscle strength and FC. Inspiratory muscle strength was evaluated based on maximal inspiratory pressure (MIP). IMW was defined as MIP values less than 70% of the predicted value. FC was evaluated using the Incremental Shuttle Walk test (ISWT). Patients whose predicted peak oxygen uptake (VO2peak) over the distance walked during the ISWT was less than 16mL/kg/min were considered to have FC impairment. Associations between variables were assessed by linear and logistic regression, with adjustment for age, sex, body mass index (BMI), presence of diabetes and hemoglobin level. Receiver-operating characteristic (ROC) analysis was used to determine different cutoff values of the MIP for normal inspiratory muscle strength and FC., Results: Sixty-five ERSD patients (67.7% male), aged 48.2 (44.5-51.9) years were evaluated. MIP was an independent predictor of the distance walked during the ISWT (R2 = 0.44). IMW was an independent predictor of VO2peak < 16mL/kg/min. (OR = 5.7; p = 0.048) in adjusted logistic regression models. ROC curves showed that the MIP cutoff value of 82cmH2O had a sensitivity of 73.5% and specificity of 93.7% in predicting normal inspiratory strength and a sensitivity and specificity of 76.3% and 70.4%, respectively, in predicting VO2peak ≥ 16mL/kg/min., Conclusions: IMW is associated with reduced FC in hemodialysis patients. Evaluation of the MIP may be important to functional monitoring in clinical practice and can help in the stratification of patients eligible to perform exercise testing.
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- 2017
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9. Salivary concentrations of cortisol and testosterone and prediction of performance in a professional triathlon competition.
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Balthazar CH, Garcia MC, and Spadari-Bratfisch RC
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- Adult, Humans, Male, Pituitary-Adrenal System physiology, Saliva metabolism, Hydrocortisone analysis, Physical Endurance physiology, Saliva chemistry, Testosterone analysis
- Abstract
The aim of this study was to examine salivary cortisol and testosterone concentrations in professional male athletes during a short triathlon competition using non-invasive methods, and to determine whether these hormone concentrations could be accurate predictors of performance. Eight adult male athletes (age, mean ± SEM: 27.8 ± 3.2 years; body mass index: 21.66 ± 0.42) in a professional triathlon team volunteered to participate in this study. Saliva samples were taken on the competition day and 7 days after competition on a rest day. The performance of the athletes was assessed by their rank order in the competition. Salivary cortisol concentrations were greater on the competition day than on the rest day in the early morning, immediately after waking up, 30 min later, immediately before the start of the competition, and later in the evening. Testosterone concentrations were greater on the competition day in the morning and in the evening. The diurnal rhythm of both cortisol and testosterone concentrations was maintained on both days and the testosterone/cortisol ratio (T/C ratio) was similar between days. The performance of the athletes was positively correlated with salivary cortisol concentration in the early morning of the competition day, but was not correlated with testosterone concentrations at any of the time points. In conclusion, early morning salivary cortisol concentration, but not T/C ratio, could be used to predict performance in athletes during a professional triathlon competition.
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- 2012
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10. The Grammar of Information: Challenges for Older Students With Language Impairments.
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Scott CM and Balthazar CH
- Abstract
Purpose: The purpose of this article is to describe the nature of informational (expository) language in terms of unique grammatical characteristics and discuss applications for assessment and intervention for older school-age children and adolescents with language impairments., Methods: Information presented is based on a selected literature review of topics including the nature of academic texts, expository text processing of older children and adolescents with language impairments and/or learning disabilities, and language intervention studies that target higher level language in the same populations., Results: We summarize key grammatical strategies found in informational text: (1) complex nominal (noun phrase) groups, (2) clausal subordination, and (3) theme and information mechanisms. Although facility with these structures is not routinely or systematically tested by language clinicians, we highlight assessment procedures useful this purpose. Promising intervention evidence suggests that grammatical features characteristic of informational text can be targeted with positive results for students who struggle with this aspect of higher level language., Conclusions: Success comprehending and producing informational text requires unique grammatical knowledge. A qualitative literature review is used to derive best practices in assessment and intervention with school-age children who are particularly challenged by these types of texts.
- Published
- 2010
11. Effects of blockade of central dopamine D1 and D2 receptors on thermoregulation, metabolic rate and running performance.
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Balthazar CH, Leite LH, Ribeiro RM, Soares DD, and Coimbra CC
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- Animals, Benzazepines administration & dosage, Benzazepines pharmacology, Dopamine Antagonists administration & dosage, Injections, Intraventricular, Male, Muscle Fatigue physiology, Oxygen Consumption drug effects, Rats, Rats, Wistar, Salicylamides administration & dosage, Salicylamides pharmacology, Body Temperature Regulation drug effects, Dopamine Antagonists pharmacology, Dopamine D2 Receptor Antagonists, Metabolism drug effects, Receptors, Dopamine D1 antagonists & inhibitors, Running physiology
- Abstract
To assess the effects of a blockade of central D1- and D2-dopaminergic receptors on metabolic rate, heat balance and running performance, 10 nmol (2 microl) of a solution of the D(1) antagonist SCH-23390 hydrochloride (SCH, n = 6), D2 antagonist eticlopride hydrochloride (Eti, n = 6), or 2 microl of 0.15 M NaCl (SAL, n = 6) was injected intracerebroventricularly into Wistar rats before the animals began graded running until fatigue (starting at 10 m/min, increasing by 1 m/min increment every 3 min until fatigue, 5% inclination). Oxygen consumption and body temperature were recorded at rest, during exercise and following 30 min of recovery. Control experiments with injection of two doses (10 and 20 nmol/rat) of either SCH or Eti solution were carried out in resting rats as well. Body heating rate, heat storage, workload and mechanical efficiency were calculated. Although SCH and Eti treatments did not induce thermal effects in resting animals, they markedly reduced running performance (-83%, SCH; -59% Eti, p < 0.05) and decreased maximal oxygen uptake (-79%, SCH; -45%, Eti, p < 0.05) in running rats. In addition, these treatments induced a higher body heating rate and persistent hyperthermia during the recovery period. Our data demonstrate that the alteration in dopamine transmission induced by the central blockade of dopamine- D1 and D2 receptors impairs running performance by decreasing the tolerance to heat storage. This blockade also impairs the dissipation of exercise-induced heat and metabolic rate recovery during the post-exercise period. Our results provide evidence that central activation of either dopamine- D1 or D2 receptors is essential for heat balance and exercise performance.
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- 2010
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12. Performance-enhancing and thermoregulatory effects of intracerebroventricular dopamine in running rats.
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Balthazar CH, Leite LH, Rodrigues AG, and Coimbra CC
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- 3,4-Dihydroxyphenylacetic Acid metabolism, Animals, Brain metabolism, Dopamine administration & dosage, Dopamine metabolism, Energy Metabolism drug effects, Hippocampus drug effects, Hippocampus metabolism, Hypothalamus drug effects, Hypothalamus metabolism, Injections, Intraventricular, Male, Oxygen Consumption drug effects, Oxygen Consumption physiology, Preoptic Area drug effects, Preoptic Area metabolism, Rats, Rats, Wistar, Body Temperature Regulation drug effects, Dopamine pharmacology, Psychomotor Performance drug effects, Running physiology
- Abstract
To assess the role of central dopamine on metabolic rate, heat balance and running performance, 2.0 microL of 5 x 10(-3)M dopamine solution (DA) or 0.15M NaCl (SAL) was intracerebroventricularly injected in Wistar rats 1 min before running on a motor-driven treadmill, according to a graded exercise protocol, until fatigue. Oxygen consumption (VO(2)) and body temperature (T(b)) were recorded at rest, during exercise, and after 30 min of recovery. DA induced a marked increase in workload (approximately 45%, p<0.05). At fatigue point, DA-injected rats attained approximately 29% higher maximum oxygen consumption (VO(2max)) and approximately 0.75 degrees C higher T(b) than SAL-injected rats. Despite the higher VO(2max) and T(b) attained during exercise, DA-treated rats reached VO(2) basal values within the same recovery period and dissipated heat approximately 33% faster than SAL-treated rats (p<0.05). The mechanical efficiency loss rate was approximately 40% lower in DA than in SAL-treated rats (p<0.05), however, the heat storage was approximately 35% higher in the DA group (p<0.05). Our results demonstrate that increased DA availability in the brain has a performance-enhancing effect, which is mediated by improvements in the tolerance to heat storage and increases in the metabolic rate induced by graded exercise. These data provide further evidence that central activation of dopaminergic pathways plays an important role in exercise performance.
- Published
- 2009
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13. Central angiotensin AT1 receptors are involved in metabolic adjustments in response to graded exercise in rats.
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Leite LH, Lacerda AC, Balthazar CH, Marubayashi U, and Coimbra CC
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- Angiotensin II Type 1 Receptor Blockers metabolism, Animals, Blood Glucose metabolism, Fatty Acids, Nonesterified blood, Lactic Acid blood, Losartan metabolism, Male, Random Allocation, Rats, Rats, Wistar, Running physiology, Energy Metabolism, Oxygen Consumption physiology, Physical Conditioning, Animal physiology, Receptor, Angiotensin, Type 1 metabolism
- Abstract
To investigate the influence of central angiotensin AT1-receptors blockade on metabolic adjustments during graded exercise, Losartan (Los) was intracerebroventricularly injected in rats before running until fatigue. Oxygen consumption (VO2) was measured (n=6) and blood samples collected (n=7) to determine variations of glucose, lactate and free fatty acids (FFA). Los-rats exhibited a hyperglycemic response, already observed at 20% of maximal work, followed by a higher lactate levels and FFA mobilization from adipose tissue. Despite the reduced total time to fatigue and the higher VO2 associated with reduced mechanical efficiency, exercise led to the attainment of similar levels of effort in both groups. In summary, central AT1-receptor blockade during graded exercise induces hyperglycemia and higher FFA mobilization from adipose tissue at low exercise intensities in rats running at the same absolute exercise intensity. These data suggest that the central angiotensinergic system is involved in metabolic adjustments during exercise since central blockade of AT1-receptors shifts energy balance during graded exercise, similarly to situations of higher and premature sympathetic activation.
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- 2009
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14. Exercise capacity is related to calcium transients in ventricular cardiomyocytes.
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Prímola-Gomes TN, Campos LA, Lauton-Santos S, Balthazar CH, Guatimosim S, Capettini LS, Lemos VS, Coimbra CC, Soares DD, Carneiro-Júnior MA, Quintão-Júnior JF, Souza MO, Cruz JS, and Natali AJ
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- Animals, Calcium-Binding Proteins metabolism, Kinetics, Male, Muscle Fatigue, Rats, Rats, Wistar, Ryanodine Receptor Calcium Release Channel metabolism, Sarcoplasmic Reticulum Calcium-Transporting ATPases metabolism, Sodium-Calcium Exchanger metabolism, Time Factors, Calcium Signaling, Exercise Tolerance, Heart Ventricles metabolism, Myocardial Contraction, Myocytes, Cardiac metabolism, Physical Exertion
- Abstract
The aim of the present study was to evaluate the Ca2+ handling and contractility properties of cardiomyocytes isolated from rats with high intrinsic aerobic exercise capacity. Standard-performance (SP) and high-performance (HP) rats were categorized with a treadmill progressive exercise test according to the exercise time to fatigue (TTF). The SP group included rats with TTF between 16.63 and 46.57 min, and the HP group included rats with TTF>46.57 min. Isolated ventricular cardiomyocytes were dissociated from the hearts of SP and HP rats, and intracellular global Ca2+ ([Ca2+]i) transients were measured. The [Ca2+]i transient peak was increased in the HP group relative to the SP group (5.54+/-0.31 vs. 4.18+/-0.12 F/F0; P
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- 2009
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15. Central AT(1) receptor blockade increases metabolic cost during exercise reducing mechanical efficiency and running performance in rats.
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Leite LH, Lacerda AC, Balthazar CH, Marubayashi U, and Coimbra CC
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- Angiotensin II metabolism, Animals, Biomechanical Phenomena, Body Temperature Regulation drug effects, Calorimetry, Indirect, Injections, Intraventricular, Losartan pharmacology, Male, Muscle Fatigue physiology, Oxygen Consumption drug effects, Rats, Rats, Wistar, Angiotensin II Type 1 Receptor Blockers pharmacology, Energy Metabolism drug effects, Physical Exertion physiology, Running physiology
- Abstract
The effect of central angiotensin AT(1) receptor blockade on metabolic rate and running performance in rats during exercise on a treadmill (18 m x min(-1), 5% inclination) was investigated. Oxygen consumption (VO(2)) was measured, using the indirect calorimetry system, while the animals were exercising until fatigue after injection of 2 microL of losartan (Los; 60 nmol, n=9), an angiotensin II AT(1) receptor antagonist, or 2 microL of 0.15 M NaCl (Sal, n=9) into the right lateral cerebral ventricle. Mechanical efficiency (ME) and workload (W) were calculated. The W performance by Los-treated animals was 29% lesser than in Sal-treated animals (p<0.02). During the first 10 min of exercise (dynamic state of exercise), there was a similar increase in VO(2), while ME remained the same in both groups. Thereafter (steady state of exercise), VO(2) remained stable in the Sal group but continued to increase and stabilized at a higher level in Los-treated animals until fatigue. During the steady state of exercise there was a sharper reduction in ME in Los-treated rats compared to Sal-treated animals (p<0.01) that was closely correlated to W (r=0.74; p<0.01). Our data showed that AT(1) receptor blockade increases metabolic cost during exercise, reducing mechanical efficiency. These results indicate that central angiotensinergic transmission modulates heat production, improving ME during the steady state of exercise.
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- 2007
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16. Chronic treatment with bromocriptine modifies metabolic adjustments in response to restraint stress in rats.
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Balthazar CH, Ribeiro Oliveira A Jr, Marubayashi U, dos Reis AM, and Coimbra CC
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- Animals, Blood Glucose analysis, Fatty Acids, Nonesterified blood, Lactates blood, Male, Rats, Rats, Wistar, Bromocriptine pharmacology, Dopamine Agonists pharmacology, Restraint, Physical, Stress, Physiological metabolism
- Abstract
1. We investigated the influence of bromocriptine (BR) chronic treatment in the autonomic adjustments to energetic metabolism during restraint stress (RS). To achieve this, Wistar male rats were chronically treated with BR before the application of RS. The rats were divided into two groups: those treated with BR and control rats, treated with saline. 2. Chronic treatment with BR did not affect rat growth and induced a 20% higher basal plasma glucose concentration. During RS, BR rats presented higher plasma glucose concentrations than the control animals. Despite this, the 30-min analysis of the areas under the glucose curve showed that the control rats presented a hyperglycemic response to RS two-fold greater than the BR rats. 3. RS induced an increase in plasma lactate concentration in both groups of rats; however, the 30-min analyses under the lactate curves showed that BR rats presented a lactate response to RS three times higher than control rats. 4. RS induced an increase in plasma free fatty acids (FFA) concentration in both groups; however, plasma FFA concentration of BR rats returned to the basal values at the end of RS. In contrast, in the control group, this concentration continued to rise until the end of RS. 5. The results showed that BR chronic treatment shifts the balance of substrate utilization in response to RS, suggesting that the essential role of lactate in the metabolism homeostasis may be altered by chronic BR treatment.
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- 2007
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17. Central nitric oxide inhibition modifies metabolic adjustments induced by exercise in rats.
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Lacerda AC, Marubayashi U, Balthazar CH, Leite LH, and Coimbra CC
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- Animals, Behavior, Animal, Blood Glucose drug effects, Brain drug effects, Enzyme Inhibitors pharmacology, Fatty Acids, Nonesterified blood, Injections, Intraventricular methods, Lactic Acid blood, Male, Metabolism drug effects, NG-Nitroarginine Methyl Ester pharmacology, Rats, Rats, Wistar, Brain metabolism, Metabolism physiology, Nitric Oxide physiology, Physical Conditioning, Animal physiology
- Abstract
The influence of the central nervous system on metabolic function is of interest in situations deviating from basal states, such as during exercise. Our previous study in rats demonstrated that central nitric oxide (NO) blockade increases metabolic rate, reducing mechanical efficiency during exercise. To assess the role of brain nitric oxide in the plasma glucose, lactate and free fatty acids (FFAs) concentrations of rats submitted to an incremental exercise protocol on a treadmill until fatigue, 1.43 micromol (2 microl) of N(omega)-nitro-l-arginine methyl ester (L-NAME, n=6), a NO synthase inhibitor, or 2 microl of 0.15M NaCl (SAL, n=6) was injected into the lateral cerebral ventricle (icv) of male Wistar rats immediately before exercise (starting at 10 m/min, with increments of 1m/min every 3 min until fatigue, 10% inclination). Blood samples were collected through a chronic jugular catheter at rest and during exercise until fatigue. During exercise, the L-NAME-treated animals had the following metabolic response compared to controls: (1) an increased hyperglycemic response during the first 60% of time to fatigue; (2) higher plasma lactate levels; and (3) a significant transitory increase in plasma free fatty acids during the dynamic phase of exercise that returned to basal levels earlier than controls during the steady state phase of exercise. In addition L-NAME-treated rats fatigued earlier than controls. The data indicate that the inhibition of the brain nitrergic system induced by icv L-NAME treatment disrupted the accuracy of the neural mechanism that regulates plasma glucose and free fatty acids mobilization during exercise in rats.
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- 2006
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18. Evidence that brain nitric oxide inhibition increases metabolic cost of exercise, reducing running performance in rats.
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Lacerda AC, Marubayashi U, Balthazar CH, and Coimbra CC
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- Animals, Behavior, Animal, Brain drug effects, Enzyme Inhibitors pharmacology, Exercise Test methods, Male, NG-Nitroarginine Methyl Ester pharmacology, Oxygen Consumption drug effects, Rats, Rats, Wistar, Time Factors, Brain metabolism, Nitric Oxide metabolism, Physical Conditioning, Animal, Running physiology
- Abstract
To assess the role of nitric oxide (NO) in the metabolic rate and running performance of rats submitted to exercise on a treadmill, 1.43 micromol (2 microL) of Nomega-nitro-L-arginine methyl ester (L-NAME, n=6), a NO synthase inhibitor, or 2 microL of 0.15M NaCl (SAL, n=6) was injected into the lateral cerebral ventricle of male Wistar rats immediately before the animals started running (18m min(-1), 5% inclination). Oxygen consumption (VO2) was measured at rest, during the exercise until fatigue and thereafter during the 30 min of recovery using the indirect calorimetry system. Mechanical efficiency (ME) was also calculated during the running period. During the first 11 min of exercise, there was a similar increase in VO2 while ME remained the same in both groups. Thereafter, VO2 remained stable in the SAL group but continued to increase and remained higher in the L-NAME group until fatigue. The L-NAME-treated rats also showed a sharper decrease in ME than controls. In addition, there was a significant reduction in workload performance by L-NAME-treated animals compared to SAL-treated animals. This suggests that central blockage of nitric oxide increases metabolic cost during exercise, reduces mechanical efficiency and decreases running performance in rats.
- Published
- 2006
- Full Text
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